I've read evry post I can find on this problem but still need help. At about 2500 rpm my engine starts making a knock or rattle type sound. When I shift it begins again at about 2500. I can't make it do it while it's just sitting in the driveway running so I can't find it. I've listened with a mechanics stethoscope just about everywhere on the engine also.

When it's making the noise I can make it quit just by backing off the throttle a hair or by giving it more throttle. I looked at the timing chain and didn't see any indication that the tensioners are loose or broken. The chain seems to be a hair loose though on the exhaust side of the engine while the other side is tighter. I think I was able to see that the tensioners are both holding it in towards the bottom sprocket.

It almost seems to be coming from the EFI housing. I don't know. It doesn't seem to be in the valve train anywhere. I checked them for adjustment.

I've looked at the pulleys, belts, clutch fan isn't loose. Changed the timing both ways...advance and retard.

Other than the noise it runs great. I'm afraid if I can't track it down something major is going to happen.

Any thoughts would be appreciated.

Had similar problem on mine. Turned out to be an exhaust leak. Noise stopped after replacing cat-back. I was convinced it was a manifold crack or something worse. The source of noises on the 22RE can be deceiving.

Sounds like spark knock. Retarding the timing should have lessened the noise. Set your timing to 5dbtdc with te1 and e1 bridged. Run your gas tank about empty and then fill her up on PREMIUM [color:"red"] [/color] gas, and see if you still have the rattling.

maybe a rod knock?
does it do it equally under free rev as under load?